Inyouchuu Episode 2 WTF?

I just want to know one thing, what the hell happend at the end. What did she say at the end and who exactly killed him, her or the demon and why.

PS I didnt put this in the Request section because im not requesting a video or how to find something, I just want to know what the hell happend.

Im talking about the part where the human boy is hit by a lightning bolt, turns green, and crumbles to the ground.